The ear for music
At a very early age of around 5 months, babies can distinguish an upbeat tune from a lineup of gloomy and sad tunes. There was a research done in order to find out how babies make sense of the world around them before they can even talk.
At this early age, the way they communicate is through emotions. Music to them is a form of emotion.
When the researchers played a sad music, the babies showed an emotionally neutral face. On the other hand, when an upbeat tune is played they seem to show a lot of interest.
So what makes a sad and a happy tune? The happy songs are all in major keys while sad songs are in minor keys and had a slower beat and long melodic rhythms.